Cold starting of internal combustion engines, particularly small engines in chainsaws, snow blowers and the like, has been and remains a problem in the art. Devices such as chainsaws which are frequently employed under adverse starting conditions typically embody a manual priming system, as illustrated in U.S. Pat. No. 4,271,093 (June 2, 1981), in which a resilient cap or bulb is mounted on or adjacent to the engine carburetor and may be manually activated by an operator for drawing fuel into the carburetor and purging air therefrom. Excessive activation of the cap or bulb when the engine is cold typically results in ejection of fuel into the surrounding environment. Moreover, activation of the priming system when the engine is warm, or where the engine fails to start on the first attempt, can so flood the engine carburetor that the engine will not start at all.
It is therefore a general object of the present invention to provide a system for priming and purging air from the fuel lines and reservoir of an internal combustion engine so as to facilitate cold starting thereof and which overcomes the deficiencies set forth above. More specifically, it is an object of the present invention to provide a system of the described character which will facilitate one-pull starting of the engine over an extended engine temperature range of -40.degree. F. to +150.degree. F., which is so constructed as to prevent misuse by an inexperienced operator, including particularly over priming of the engine, which is powered by replaceable batteries, which is inexpensive in assembly and reliable over an extended operating lifetime, and which requires minimum adaptation to particular engine designs and requirements.